1. Field of the Invention
The invention relates to the use of organic polyisocyanate adducts in the preparation of polyurethanes. More particularly, the invention relates to the use of the reaction product of from 0.5 percent by weight to 5 percent by weight of a reactive diamine such as bis(4-aminocyclohexyl)methane or isophorone diamine with organic polyisocyanates in the preparation of polyurethane foams and elastomers. The reaction product is prepared at a temperature between 135.degree. C. and 200.degree. C., preferably between 150.degree. C. and 175.degree. C.
2. Description of the Prior Art
The preparation of high resiliency polyurethane foams by the reaction of a polyol with a polyisocyanate employing a cross-linking agent is well known in the art. As a substitute for 4,4'-methylene-bis(2-chloroaniline), suspected of being carcinogenic, the use of bis(4-aminocyclohexyl)methane as a component in high resiliency polyurethane foam compositions has been described in U.S. Pat. No. 4,210,728. Toluene diisocyanate adducts of bis(4-aminocyclohexyl)methane and isophorone diamine prepared at a temperature of 130.degree. C. to 200.degree. C. have been disclosed in U.S. Pat. No. 4,147,714 for use in high quality lacquers which are weather resistant and stable to light. The reaction mixtures are disclosed as normally free from excess diisocyanate.
The prior art does not disclose high resiliency polyurethane foams or a way of making same with improved stability which avoids problems such as (1) skinning over of the resin blend by the reaction of the amine with atmospheric moisture and (2) poor stability during the foaming reaction whereby mold leaks cause collapse of the foam. Further, the prior art does not disclose high modulus polyurethane elastomers of improved properties of heat sag and modulus ratio made with the organic polyisocyanate adducts of the invention.
The present invention is directed toward novel reactive compositions which provide polyurethane free rise foams of improved stability, firmness and openness of cell structure; molded foams of improved ILD; and high modulus polyurethane elastomers of improved heat sag and modulus ratio.